Blood glucose monitoring: is blood glucose monitoring for many of those people with type 2 diabetes really necessary in the management of the condition?

Type 2 diabetes is a condition of impaired glucose metabolism, due to either inslin insufficiency and/or insulin resistance. First line therapy is non-pharmacological, focusing on changes that can be made to the person's lifestyle, particularly healthy eating and physical activity. Diabetes tablets and/or insulin therapy may be required.

The person with diabetes can measure their blood glucose levels using a blood glucose meter. This provides the person and their health professional with a measure of their day-today control. However, self-monitoring of blood glucose is an area of significant debate among health professionals. Self blood glucose monitoring (SBGM) is an invasive procedure, which requires the person with diabetes to prick their own finger to obtain a drop of blood. Self blood glucose monitoring is a valuable toot and regular testing is essential for people with type 1 diabetes. But blood glucose monitoring is most effectively used in type 2 diabetes when a person is treated with a sulphonylurea (which could lead to hypoglycaemia) or when changes to treatment regimens are being made due to inadequate glycaemic control. There is limited evidence for the benefit of regular, routine testing in patients with type 2 diabetes who have a low risk of hypoglycaemia.

Haemoglobin A1C is another effective measure of glycaemic control This test measures how much glucose has attached to the A1C portion of the haemoglobin over the past 120 days (lifespan of haemoglobin) and gives an indication of glycaemic control over this time. Evidence suggests that regular measurement of HbA1C in people with type 2 diabetes who are not on sulphonylureas or insulin is as effective in guiding treatment recommendations as regular SBGM.

So what happens in practice? There appears to be almost an automatic assumption that initiating self-monitoring of blood glucose is required, with testing often perceived to do no harm. So we need to ask ourselves some important questions. While SBGM may be useful at diagnosis, are we really doing the best for these people asking them to test for the rest of their lives? For SBGM to be effective, the results must be used for something. How many people do you know in your practice who SBGM but never do anything with the results? Are we doing more harm than good? What is our justification for instructing people managed with diet alone and/or biguanide (metformin) therapy, with adequate glycaemic control to keep testing regularly, and what is the evidence for this? As previously mentioned, there is little evidence to suggest that regular SBGM in this group of people makes any difference to outcomes.

Earlier in the year, I was asked to sit on an expert advisory group for PHARMAC, the pharmaceutical management agency. This was in the area of diabetes management and in particular had a focus on the self-monitoring of blood glucose. At this meeting, we heard that around $19 million was spent on diabetes test strips annually! This exceeded what was spent on all oral hypoglycaemics and insulins combined. This is understandably an important issue for us as health professionals and for the government drug-funding agency.

So what does this mean for us as nurses? Next time you are talking with a person who has type 2 diabetes, critically consider whether they really need to be regularly self monitoring their blood glucose. Staying well with diabetes is best achieved by a focus on healthy eating, physical activity and medication (as required and directed). Monitoring the effectiveness of these therapies in this group of people may be effectively done through HbA1C measurement, using SBGM only with a specific purpose.

* References are available from Helen Snell at: [e-mail].

Helen Snell RN, NP, MN, M Phil (Nursing) is a nurse practitioner, diabetes and related conditions, at MidCentral District Health Board's Diabetes Service.